1. Field of the Invention
The present invention relates to a liquid supplying apparatus for supplying liquid to a liquid ejection head through a filter, a liquid ejecting apparatus, and a liquid supplying method.
2. Description of the Related Art
A liquid supplying apparatus is exemplified by an ink supplying apparatus for supplying ink (i.e., liquid) contained in an ink tank (i.e., a liquid container) to an inkjet printing apparatus serving as a liquid ejecting apparatus. The printing apparatus is adapted to eject the ink, supplied by the ink supplying apparatus, from an inkjet print head (i.e., a liquid ejection head) so as to print an image. The ink supplying apparatus supplies the ink through a filter in order to inhibit the intrusion of waste to the print head. A filter chamber provided with the filter is divided into a first filter chamber and a second filter chamber via the filter. The ink contained in the ink tank is supplied to the print head through the first filter chamber, the filter, and the second filter chamber. An air bubble is liable to reside in the first filter chamber. In a case where the air bubble largely grows, the ink is inhibited from being supplied, possibly resulting in ink ejection deficiency at the print head.
Japanese Patent Laid-Open No. 2000-103074 discloses a method for pressurizing and circulating (pressure-circulating) ink between a first filter chamber and an ink tank so as to purge an air bubble in the ink contained in the ink tank in order to purge the air bubble residing in the first filter chamber.
In order to purge the air bubble residing in the first filter chamber at a high speed, it is necessary to increase a circulation amount of ink between the first filter chamber and the ink tank. A large-sized print head for ejecting a large quantity of ink is used in the business-grade printing field, in particular, thereby increasing the quantity of air bubbles residing in the first filter chamber. Thus, it is necessary to increase a circulation amount of ink so as to purge the air bubbles at a higher speed.
As disclosed in Japanese Patent Laid-Open No. 2000-103074, it is necessary to increase ink pressurizing force so as to increase the ink circulation amount in the method for pressure-circulating ink between the first filter chamber and the ink tank. However, in a case where the ink pressurizing force is increased, there is a possibility that the air bubble residing in the first filter chamber passes the filter, and then, intrudes into the print head through the second filter chamber.